The invention relates to surgical bipolar scissors with two scissor blades pivotable relative to each other, the first of which consists of an electrically conductive material and the second of an electrically insulating material on the side thereof facing the first scissor blade, but of an electrically conductive material on the side thereof facing away from the first scissor blade.
Surgical bipolar scissors of this kind are known, for example, from U.S. Pat. No. 5,324,289. With bipolar scissors of this design it is possible to make hemostatic incisions, i.e., upon applying an alternating voltage to the two electrically conductive parts of the two scissor blades a current flows in the area of the incision point between these and owing to the provision of an insulating layer on the one scissor blade it does not run directly from scissor blade to scissor blade, but through the tissue positioned in the area of the incision point in which bleeding can in this way be stopped.
In the known surgical bipolar scissors, insulating materials are disposed on one of the two scissor blades in the cutting area, for example, by means of coating in a gas stream or by applying thin ceramic layers which are joined to the metallic scissor blade.
Starting from this prior art, the object underlying the invention is to design surgical bipolar scissors so that these are, on the one hand, particularly effective, and, on the other hand, particularly stable in the cutting edge area.
This object is accomplished with surgical bipolar scissors of the kind described at the outset in accordance with the invention in that the second scissor blade comprises a ceramic shaped body in the form of a complete scissor blade extending beyond a bearing point of the two scissor blades, in that a metallic support blade likewise extending beyond the bearing point rests against the outer side of the shaped body over the surface thereof, and in that the shaped body and the support blade are permanently connected to each other at their contact surface.
In contrast to known bipolar scissors, the second scissor blade itself is constructed as a ceramic shaped body so that a metallic scissor blade is located opposite a scissor blade consisting of a ceramic material in the tool area, and these two parts together perform the cutting operation.
An additional support blade is provided for stabilizing the ceramic shaped body and forming a counter electrode for the metallic scissor blade. The support blade is positioned on the outer side of the ceramic shaped body and is connected thereto over the surface thereof. Both the ceramic shaped body and the support blade on the outer side thereof extend beyond the bearing point of the scissor blade so that the supporting action of the support blade becomes effective precisely in this area which is subjected to very high mechanical stress.
Provision may be made in a preferred embodiment for the shaped body to form a bearing sleeve which surrounds a bearing shaft of the two scissor blades and extends through the first scissor blade. A complete insulation of the two scissor blades from each other is thereby ensured, also in the bearing area. It is thus possible to use a bearing shaft made of a conductive material, in particular, a metallic bearing shaft, which can then also be simultaneously used as electrical connection of the support blade to a connection of a voltage source.
Provision is made in a preferred embodiment for the shaped body and the support blade to comprise projections and recesses which engage one another in a positively locking manner. Owing to this positive locking connection, the ceramic shaped body is supported optimally so that the surface connection between shaped body, on the one hand, and support blade, on the other hand, is maintained even under high stress.
In particular, provision may be made for the shaped body to carry a longitudinal rib which engages in a longitudinal groove of the support blade in a positively locking manner. The longitudinal rib and the longitudinal groove preferably extend over the entire length of the shaped body.
Further provision may be made for a metal extension element to rest against the shaped body in the area of the bearing point thereof on the side thereof opposite the support blade and to be connected to the shaped body. The extension element is, in turn, connected to a part of a pivot mechanism for pivoting the scissor blades. The pivot mechanism has to transmit large forces and so it is expedient to use metal as material therefor, but this metal is electrically insulated from the support blade by the shaped body interposed therebetween, so that it is ensured that an electrical connection does not occur between the pivot mechanism, on the one hand, and the support blade, on the other hand.
It is expedient for the shaped body and the extension element to comprise projections and recesses engaging one another in a positively locking manner so that the connection between the two parts is thereby also stabilized, in particular, for the transmission of the pivoting moments.
The shaped body and the support blade can be joined surface-to-surface to one another in any chosen way. In particular, they are soldered to each other.
It is expedient for the shaped body and the support blade to be connected to each other in the cutting area by a soft solder, in the area of the bearing point by a hard solder.
As a whole, one thus obtains a sandwich-like second scissor blade which is made up of the shaped body and the support blade and which like the first scissor blade can be inserted as a structural unit into the surgical instrument.